Method for improving warm-up of an engine

Abstract

A method is disclosed for heating a liquid supplied to an engine of a motor vehicle by a pump when the temperature of the liquid is low, thereby reducing the operating efficiency of the engine. The method comprises inefficient operation of the pump by constricting flow to create heat that is transferable to the liquid. Inefficient operation of the pump is enacted when service brakes are applied and the vehicle is decelerating to minimize negative impact on fuel economy and overall engine efficiency.

The invention claimed is: 
     
       1. A method for improving warm-up of an engine of a vehicle comprising:
 operating a flow control valve positioned downstream of a pump to circulate a liquid through the engine via a return line positioned downstream of the flow control valve; 
 operating the pump in a normal operating mode when the liquid is above a predefined threshold temperature; and 
 activating a heating mode of operation for the pump if the vehicle is decelerating and the liquid is below the predefined threshold temperature; 
 wherein, in the heating mode of operation, the pump is operated less efficiently than in the normal mode so as to generate more heat transferable from the pump to the liquid passing through the pump. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the vehicle further comprises service brakes to decelerate the vehicle in response to a driver input, and further comprising activating the heating mode of operation to heat the liquid passing through the pump if the service brakes of the vehicle have been activated. 
     
     
       3. The method as claimed in  claim 2 , wherein the method further comprises activating the heating mode of operation to heat the liquid passing through the pump if the service brakes of the vehicle have been activated sufficiently to produce a deceleration of the vehicle above a predefined level. 
     
     
       4. The method as claimed in  claim 1 , wherein, in the heating mode of operation, a flow of liquid from the pump is more restricted than in the normal mode so as to generate more heat transferable to the liquid passing through the pump. 
     
     
       5. The method as claimed in  claim 1 , wherein the pump is driven by the engine. 
     
     
       6. The method as claimed in  claim 1 , wherein the liquid is oil. 
     
     
       7. A vehicle comprising:
 an engine; 
 a flow control valve positioned downstream of a pump operable in a normal operating mode and a heating mode of operation to circulate a liquid through the engine; and 
 a controller, wherein the controller is operable to operate the flow control valve in the heating mode of operation to heat the liquid passing through the pump only if the vehicle is decelerating; 
 wherein, in the heating mode of operation, the pump is operated less efficiently than in the normal mode so as to generate more heat transferable from the pump to the liquid passing through the pump. 
 
     
     
       8. The vehicle as claimed in  claim 7 , further comprising service brakes to decelerate the vehicle in response to a driver input, and the controller is operable to operate the flow control valve in the heating mode of operation to heat the liquid passing through the pump if the service brakes of the vehicle have been activated. 
     
     
       9. The vehicle as claimed in  claim 8 , wherein the controller is operable to operate the flow control valve in the heating mode of operation to heat the liquid passing through the pump if the service brakes of the vehicle have been activated sufficiently to produce a deceleration of the vehicle above a predefined level. 
     
     
       10. The vehicle as claimed in  claim 9 : wherein the controller is operable to operate the flow control valve in the heating mode of operation if a temperature of the liquid passing through the pump is below a predefined temperature. 
     
     
       11. The vehicle as claimed in  claim 7 , wherein the pump is driven by the engine. 
     
     
       12. The vehicle as claimed in  claim 7 , wherein the liquid is one of oil and coolant. 
     
     
       13. The vehicle as claimed in  claim 7 , wherein the vehicle has an oil pump and a coolant pump, each operable in a normal operating mode and a heating mode of operation to circulate a respective liquid through the engine, and the controller is operable to operate the flow control valve in the heating mode of operation to heat the respective liquid passing through the oil pump and the coolant pump if the vehicle is decelerating. 
     
     
       14. A method for an engine comprising:
 opening a flow control valve in an oil circuit when a temperature of oil within the oil circuit is above a predefined threshold temperature; and 
 constricting the flow of oil within the oil circuit by turning a butterfly valve only when a temperature of the oil is below the predefined threshold temperature and a vehicle is operating in an over-run situation. 
 
     
     
       15. The method as claimed in  claim 14 , further comprising constricting the flow of oil within the oil circuit by routing the flow of the oil through a restricted line, the restricted line being blocked to the flow of the oil when the temperature of the oil is above a predefined threshold temperature. 
     
     
       16. The method as claimed in  claim 15 , further comprising constricting the flow of oil within the oil circuit by routing the flow of the oil through the restricted line which is of smaller diameter than lines that are not blocked when the temperature of the oil is above a predefined threshold temperature.